GB893304A - Photopolymerization of monomers containing the ch=c grouping - Google Patents

Abstract

Compounds containing the grouping CH2=C< are polymerized by exposing them to electromagnetic radiation having a wavelength of from 10-1 to 10-10 cm. in the presence of a thallium compound as a polymerization catalyst. Polymerizable compounds specified are acrylamide, methacrylamide, N-hydroxymethyl and N-hydroxyethyl acrylamides, acrylic and methacrylic acids, calcium acrylate, acrylonitrile, methyl and ethyl acrylates, methyl methacrylate, vinyl acetate, butyrate and benzoate, vinyl methyl, ethyl isopropyl and isobutyl ethers, vinyl pyrrolidone, butadiene and mixtures of ethyl acrylate and vinyl acetate, acrylonitrile and styrene and butadiene and acrylonitrile. The above compounds may be polymerized in admixture with small amounts of compounds containing at least two terminal vinyl groups, e.g. divinyl benzene, methylene-bis-acrylamide, triallyl cyanurate, divinyl ketone and diglycol diacrylate. Thallium compounds specified are thallous oxide and hydroxide, thallous salts of the common inorganic acids, thallous formate, oxalate, formate-malonate and myristate and thallous methoxide; the preferred compound is thallous nitrate. The effectiveness of the thallium compound as a catalyst may be enhanced by the use therewith of compounds such as gold, rhodium, silver and stannous salts, e.g. gold and rhodium chlorides and silver nitrate, a mixture of a gold salt and sodium nitrate, potassium iodide, thiourea, thiocyanates, ascorbic acid and dyestuffs such as cyanines, merocyanines, hemicyanines and styryls. The polymerization may be carried out in solution in water or a water-alcohol mixture, or in aqueous dispersion containing dispersing agents such as long chain fatty acid sarcosides or taurides, the reaction products of ethylene oxide with a phenol, a fatty alcohol, an amine or a fatty acid, and long chain aliphatic sulphonates. The polymerizing radiation may be ultra-violet or visible light, gamma-rays or X-rays. The examples describe the polymerization of mixtures of acrylamide and methylene-bis-acrylamide in the presence of water. The process may be used in the production of polymeric photographic images, for which purpose polymerization may be carried out in the presence of a colloid carrier, e.g. gelatin, polyvinyl alcohol, starch, glue, carboxymethyl cellulose, a polyamide, polyvinyl pyrrolidone or saponin, the photopolymerizable composition being coated on a suitable support.